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Title Shelby cars north west, factory authorized dealer for shelby automobiles


Roush Engine 427R

427R - This is our thoroughbred and has a single plane intake manifold and a “double pumper” carburetor. Maximum horsepower, maximum fun.

Technical Specs

Engine Model: 427R
Horsepower (maximum):
550 hp (with Victor Jr. intake & 8qt. Oil Pan)
Torque (maximum): 535 ft. -lbs.
Displacement: 427 cu. in.
Block: 9.5” deck, Dart 4-bolt main
Crankshaft Type:
Forged 4340 Steel (Internally Balanced)
Bore and Stroke: 4.125” x 4.00”
Connecting Rod Type:
Forged 4340 Steel “H-beam”
Compression Ratio: 10.25:1
Wiseco Forged w/ Plasma Moly Rings & Lightweight Pins
Timing Chain: Double Roller
Camshaft Info: Roush Proprietary
Lifter Type: Hydraulic Roller
Cylinder Heads: Aluminum
Intake Runner Volume:
205 cc, fully CNC ported
Combustion Chamber Volume: 61 cc
Valve Sizes: 2.08” Intake 1.600” Exhaust
Rocker Arm Ratio: 1.6:1
Spark Plugs: Autolite 3923 (or comparable)

Intake Manifold:
Single or Dual Plane available
Fuel System:
Holley 750 CFM Carburetor w/ mechanical secondaries (Electric choke available)
Fuel Requirements:
Premium Unleaded (minimum)
Max. Recommended RPM: 6,250
Firing Order: 1-3-7-2-6-5-4-8
31 to 34 degrees @ 4,000 rpm (not to exceed 35)
Oil Pump: High Output - Adjustable
Oil Pan:
Powder Coated 8 qt. Front Sump - Baffled or Dual-sump (Mustang) available *horsepower output can be reduced when engine is equipped with the Dual-sump pan
Oil Filter: Motorcraft FL1 (or comparable)
Oil Weight:
10w30 - non synthetic for first 3,000 miles
Steel, 157 tooth (Aluminum Available)
(Ford Motorsports Super High Torque (1.6kw) (or equivalent)